Hardware Support for Detecting Illegal References in a Multiapplication Real-Time Java Environment

Our objective is to adapt the Java memory management to an embedded system, e.g., a wireless PDA executing concurrent multimedia applications within a single JVM. This paper provides soft-ware, and hardware-based solutions detecting both illegal references across the application memory spaces and dangling pointers within an application space. We give an approach to divide/share the memory among the applications executing concurrently in the system. We introduce and define application-specific memory, building upon the real-time specification for Java (RTSJ) from the real-time Java expert group. The memory model used in RTSJ imposes strict rules for assignment between memory areas, preventing the creation of dangling pointers, and thus maintaining the pointer safety of Java. Our implementation solution to ensure the checking of these rules before each assignment inserts write barriers that use a stack-based algorithm. This solution adversely affects both the performance and predictability of the RTSJ applications, which can be improved by using an existing hardware support